Production and characterization of recombinant dengue virus type 4 envelope domain III protein.

Dengue fever, a mosquito-borne viral disease has become a major worldwide public health problem with a dramatic expansion in recent years. Cultivation process for production of recombinant dengue virus type 4 envelope domain III (rDen 4 EDIII) protein in Escherichia coli was developed for its diagnostic use as well as for further studies in immunoprophylaxis. The dissolved oxygen level was maintained at 20-30% of air saturation. The culture was induced with 1mM of isopropyl beta-d-thiogalactoside when dry cell weight was 13.78 g l(-1) and cells were further grown for 4h to reach 17.31 g l(-1) of culture. The protein was overexpressed in the form of insoluble inclusion bodies. The rDen 4 EDIII protein was purified by affinity chromatography and analyzed by SDS-PAGE. The final yield of purified rDen 4 EDIII protein in this method was approximately 196 mg l(-1) of culture. The purified protein was recognized in Western blot analysis and enzyme-linked immunosorbent assay (ELISA) with dengue infected human serum samples. These results show that the product has the potential to be used for the diagnosis of dengue infection or for further studies in vaccine development. This production system may also be suitable for the high yield of other recombinant dengue proteins.

Production of IgM specific recombinant dengue multiepitope protein for early diagnosis of dengue infection.

Dengue virus infections have recently undergone dramatic expansion in range, affecting several tropical and subtropical regions of the world. Early detection of dengue infection based on the identification of antibodies has emerged as a practical and reliable means of diagnosis of dengue fever. The recombinant dengue multiepitope (rDME-M) protein specific to IgM in E. coli was produced in a 5-L fermentor for use in diagnostic purpose. After fermentation, dry cell weight was approximately 11.8 g/L of the culture. The rDME-M protein was purified under denaturing conditions using single-step nickel nitrilotriacetate (Ni-NTA) affinity chromatography. The final yield of purified rDME-M protein from this method was approximately 68.5 mg/L of the culture. The purity of rDME-M protein was checked by SDS-PAGE analysis, and the reactivity of this protein was further checked by Western blotting and enzyme-linked immunosorbent assay (ELISA). The purified protein was used as an antigen in the development of an in-house dipstick ELISA and evaluated with a panel of 80 patient sera, characterized using commercially available tests for detection of dengue antibody. The results were in excellent agreement with those of IgM capture ELISA (Pan-Bio) and rapid immunochromatography (IC) test (Pan-Bio). These results show that the in-house dipstick ELISA using rDME-M protein can be used as a promising kit because of its comparable sensitivity, specificity, field applicability, and low cost.

Production, purification and characterization of recombinant dengue multiepitope protein.

Dengue is an acute mosquito-borne viral disease of humankind. Dengue fever, dengue haemorrhagic fever and dengue shock syndrome have become global public health problems in recent years. rDME-G (recombinant dengue multiepitope protein that can specifically detect IgG) was produced in a 5-litre fermenter in Escherichia coli for use in diagnosis. The culture was induced with 1 mM isopropyl beta-D-thiogalactoside and cells were further grown for 4 h before harvesting. After fermentation, dry cell weight resulted in approx. 16.2 g/l. The rDME-G protein was purified from inclusion bodies using affinity chromatography. The final yield of purified rDME-G protein from fermentation resulted in approx. 168 mg/l of pure biologically active rDME-G protein. The purity of rDME-G protein was checked by SDS/PAGE analysis and the reactivity of this protein was further determined by Western blotting. The purified protein was used to develop an in-house dipstick ELISA and tested using a panel of 60 patient sera characterized using the commercially available tests for detection of dengue antibody. We compared our results with IgG-capture ELISA (Pan-Bio, Windsor, QLD, Australia) and rapid IC (immuno-chromatography) test (Pan-Bio). By using rDME-G protein as an antigen, in the dipstick ELISA, the results were in excellent agreement with commercial rapid IC test and IgG capture ELISA. These results show that the product has a promising potential to be used for diagnosis of dengue in both laboratory- and field-based detection systems with minimum cost and a high degree of sensitivity and specificity.